HUNTSVILLE, Alabama -- Parents of Madison County students have been alerted that two of the district's schools are facing an outbreak of pertussis, otherwise known as "whooping cough."

The Madison County Health Department on Tuesday confirmed six cases of the highly-contagious respiratory illness in the schools. Five cases have been reported at Riverton Intermediate and one case has been found at Mt. Carmel Elementary.

Geraldine Tibbs, a spokeswoman for the school district, said letters were sent home to parents informing them of the cases and making them aware of the symptoms and preventative measures that can be taken.

"Teachers and nurses are reminding students to cover and wash -- cover their mouth and nose when coughing or sneezing and wash their hands often," Tibbs said. "Parents need not be alarmed but (should) continue to monitor their children and seek professional assistance if needed."

According to the Centers for Disease Control and Prevention, it most often affects infants and children and can be fatal, particularly in babies under the age of 1.

The disease is typically spread by someone coughing or sneezing while in close contact with others. Babies often are infected by parents, caregivers or older siblings who do not even know they have been infected.

View full sizeThe progression of pertussis, a highly-contagious respiratory illness that can be fatal in very small children. (Centers for Disease Control and Prevention)

Symptoms of the illness usually develop within seven to 10 days of infection, though it can take as long as six weeks, the CDC reports. The early symptoms -- which in themselves can last for up to two weeks -- include a runny nose, low-grade fever, mild cough and apnea, or a pause in a child's breathing.

The most effective prevention is a pertussis vaccine, the CDC says. Someone who has been vaccinated can still develop the illness, but it is usually less severe.

Alabama saw a spike in pertussis cases in recent years, going from 69 cases in 2008 to 305 in 2009, the Alabama Department of Public Health reports. There were 205 cases of the illness in 2010.

Tracey England, a registered nurse with the Department of Public Health, said there were about 100 cases in 2011.

England said the Madison County outbreak is not unusual.

"Every year, we see cases spread out throughout all of the counties," England said.

Alabama schoolchildren receive pertussis protection through the tetanus-diphtheria-acellular pertussis (Tdap) vaccine. According to the health department, the vaccine was required of students entering the seventh grade this school year.

Next year, the vaccine will be required of incoming eighth-graders, with the requirement being pushed back a grade each year through 2016-2017, when it will be required of 12th-graders.

Adults are also recommended to be vaccinated for the illness if they anticipate being in close contact with an infant under the age of 1.